Builtins Medium

What does this code print?

print(sorted(["bb", "a", "ccc"], key=len))

  • ['a', 'ccc', 'bb']

  • ['a', 'bb', 'ccc']

  • ['bb', 'a', 'ccc']

  • ['ccc', 'bb', 'a']

Answer

With key=len the items are ordered by their length (1, 2, 3), not alphabetically.

What does this code print?

print(round(2.5))

  • 2

  • 3

  • 2.5

  • 2.0

Answer

Python uses banker's rounding (round half to even). 2.5 sits between 2 and 3; the even neighbour 2 wins.

What does this code print?

print(max("apple", "b"))

  • apple

  • ab

  • 5

  • b

Answer

With two positional arguments max compares them directly. Strings compare lexicographically, and 'b' > 'a', so 'b' is the larger — length is irrelevant.

What does this code print?

print(sum([[1], [2]], []))

  • [[1], [2]]

  • 3

  • [1, 2]

  • TypeError

Answer

The start value [] makes sum use list +, concatenating the inner lists into [1, 2].

What does this code print?

print(bool("False"))

  • True

  • False

  • 'False'

  • ValueError

Answer

bool on a string is about emptiness, not content. Any non-empty string is truthy, so "False" becomes True.

What does this code print?

print(int("10", 2))

  • 10

  • 10.0

  • 5

  • 2

Answer

The second argument is the base. "10" in base 2 equals decimal 2.

What does this code print?

print(list(zip([1, 2, 3], ['a', 'b'])))

  • [(1, 'a'), (2, 'b'), (3, None)]

  • [(1, 'a'), (2, 'b')]

  • [(1, 2, 3), ('a', 'b')]

  • ValueError

Answer

zip stops at the shortest iterable, so the trailing 3 is dropped.

What does this code print?

print(list(filter(None, [0, 1, 2, 0, 3])))

  • [0, 0]

  • [0, 1, 2, 0, 3]

  • [1, 2, 3]

  • [None, 1, 2, None, 3]

Answer

Passing None as the function makes filter keep only truthy items, dropping the two 0 values.

What does this code print?

print(sorted(["10", "9", "2"]))

  • ['10', '2', '9']

  • ['2', '9', '10']

  • ['2', '10', '9']

  • ['9', '2', '10']

Answer

These are strings, so they sort character by character: '1' < '2' < '9'. "10" comes first because its first character '1' is smallest.

What does this code print?

print(sum([True, True, False]))

  • TypeError

  • 2

  • 3

  • True

Answer

bool is a subclass of int: True == 1 and False == 0, so the sum is 2.

What does this code print?

print(int(3.99))

  • 3

  • 4

  • 3.99

  • 3.0

Answer

int on a float truncates toward zero (it does not round), so 3.99 becomes 3.

What does this code print?

print(list(range(10, 0, -2)))

  • [10, 8, 6, 4, 2, 0]

  • [8, 6, 4, 2, 0]

  • [10, 8, 6, 4, 2, 1]

  • [10, 8, 6, 4, 2]

Answer

range counts down by 2 from 10 and stops before the stop value 0, so 0 is not included.

What does this code print?

print(min([], default=99))

  • ValueError

  • 99

  • None

  • 0

Answer

min of an empty iterable normally raises ValueError, but the default keyword supplies a fallback instead.

What does this code print?

print(list(map(str, [1, 2, 3])))

  • [1, 2, 3]

  • '123'

  • ['1', '2', '3']

  • [str, str, str]

Answer

map applies str to each item, converting every number to its string form.

What does this code print?

print(list(enumerate(['a', 'b'], start=1)))

  • [(0, 'a'), (1, 'b')]

  • [(1, 'a'), (1, 'b')]

  • [(1, 'a'), (2, 'b')]

  • [('a', 1), ('b', 2)]

Answer

The start argument sets the first counter value, so numbering begins at 1.

What does this code print?

print("".join(sorted("banana")))

  • banana

  • aaabnn

  • abn

  • nnbaaa

Answer

sorted("banana") orders the characters into ['a', 'a', 'a', 'b', 'n', 'n'], which "".join glues back into a string.

What does this code print?

print(chr(ord('a') + 1))

  • 98

  • a

  • c

  • b

Answer

ord('a') is 97; adding 1 gives 98; chr(98) is 'b'.

What does this code print?

print(bool(" "))

  • True

  • False

  • ' '

  • 1

Answer

A string containing a single space is not empty, so it is truthy — whitespace still counts as content.

What does this code print?

print(divmod(-7, 2))

  • (-3, -1)

  • (-3, 1)

  • (-4, 1)

  • (-4, -1)

Answer

Floor division rounds toward negative infinity: -7 // 2 == -4 and -7 % 2 == 1 (the remainder takes the sign of the divisor).

What does this code print?

print(max([1, 2, 3], key=lambda x: -x))

  • 1

  • 3

  • -1

  • -3

Answer

The key negates each value, so the item with the largest key (-1 from 1) wins. max returns the original item 1, not the key.